sump

1 :  a pit or reservoir serving as a drain or receptacle for liquids: such asa :  cesspoolb :  a pit at the lowest point in a circulating or drainage system (such as the oil-circulating system of an internal combustion engine)c chiefly British :  oil pan

2 British :  crankcase

3 [German Sumpf, literally, marsh, from Middle High German — more at swamp] a :  the lowest part of a mine shaft into which water drainsb :  an excavation ahead of regular work in driving a mine tunnel or sinking a mine shaft

4 :  something resembling a sump :  sink 2